1)
Why does it say that the angel touched him a second time?
1.
Malbim: The second time, the angel did not take the form of a Rosem, rather, "Mal'ach Hashem."
2)
Why did he need to eat again?
1.
Malbim: The first time, after he ate he slept. The second time he became purified (refer to 19:6:3:2), and he would not need to sleep afterwards during his 40 day journey.
3)
Why does it say "Rav Mimecha ha'Derech"?
1.
Radak: Eliyahu did know to where he is going. He went unaware [of his destination].
2.
Malbim: You will go day and night, without sleeping.